Device for pressing a sander belt of belt sander machine



Nov. 24, 1970 TOSHIO TAKEKAWA 3,541,736

DEVICE FOR PRESSING A SANDER BELT 0F BELT SANDER MACHINE Filed April 26, 1968 3 Sheets-Sheet 1 INVENTOR 706700 TAKEKAWA Y Maw Nov. 24, 1970 TOSHIO TAKEKAWA 3,541,736

DEVICE FOR PRESSING A SANDER BELT 0F BELT SANDER MACHINE Filed April 26, 1968 3 Sheet s-Sheet 2 INVE/V TOR TOSHIO TAK E KAWA MZW Nov. 24, 1970 TOSHIO TAKEKAWA 3,

DEVICE FOR PRESSING A SANDER BELT 0F BELT SANDER MACHINE Filed April 26, 1968 s Sheets-Sheet s llVl/EN TOR TOSHIO TAK E RAW/1 mw w United States Patent 3,541,736 DEVICE FOR PRESSING A SANDER BELT 0F BELT SANDER MACHINE Toshio Takekawa, Nagoya, Japan, assignor to Takekawa Tekko Kabushiki Kaisha, Nagoya, Japan, a corporation of Japan Filed Apr. 26, 1968, Ser. No. 724,531 Int. Cl. B24b 21/08 US. Cl. 51-141 3 Claims ABSTRACT OF THE DISCLOSURE A device for pressing the sander belt of a belt sander machine according to the present invention comprises a pressure means in the form of a deformable bag containing fluid such as air under pressure and an overall pressure element made of a flexible material located under said pressure means, which pressure element is in contact with the sander belt. The device further comprises an intermediate means in the form of rollers positioned between said pressure means and said overall pressure element whereby excessive sanding of the leading and trailing end portions of the workpiece may be avoided.

The present invention relates to an improvement in or relating to a belt sander machine especially for woodworking, and more particularly to a device for pressing a sander belt of the belt sander machine against a workpiece.

In a device for pressing the sander belt now available, the overall pressure element is pressed downwardly by means of metallic springs so that the portion of the sander belt pressed thereby sands the surface of the wood workpiece fed into the belt sander machine. However, it is difiicult for such a device to force the sander belt to contact the entire surface of a workpiece which is slightly warped or had previously been planed. Thus, the finishing by sanding or grinding of the workpiece can not be uniform with the conventional spring pressing device.

In order to overcome this fault, there is proposed a sander belt pressing device having a pressure means in the form of a deformable bag or vessel made of a flexible material and containing a fluid such as air under pressure which pressure means may press the sander belt via the overall pressure element also made of a flexible material and positioned under said pressure means against the workpiece surface. According to this proposal, however, inflation or expansion of the bag may cause the flexible overall pressure element and consequently the effective surface of the sander belt to be convex, which causes too much sanding or abrasion of the leading and trailing end portions of the workpiece.

This fault is overcome by further providing an intermediate means positioned between said air cushion and said overall pressure element, which intermediate means is rigid in the direction of sander belt movement but flexible in the direction normal thereto and preferably consists of a plurality of rods arranged side by side so that the axis of each rod is parallel to the direction of sander belt movement.

An object of the present invention is, thus, to provide an improved device for pressing a sander belt against a workpiece which device has a deformable vessel containing therein a fluid such as air under pressure supplied from any suitable source to press the sander belt via a flexible overall pressure element whereby the corresponding effective portion of the running sander belt may closely fit and contact substantially every surface portion of the workpiece to be finished, even if it is slightly warped.

Another object of the present invention is to provide such a device further having an intermediate means which is rigid in the direction of movement of the sander belt but flexible in the direction normal thereto whereby excessive sanding of the leading and trailing end portions of the workpiece may be avoided.

Still further objects and advantages of this invention will be readily understood with reference to the following description and accompanying drawings, in which;

FIG. 1 illustrates a side elevation of a wide belt sander machine provided with the sander belt pressing machine of the present invention,

FIG. 2 is a front elevation of another type of machine provided with the pressing device according to the present invention,

FIG. 3 is an enlarged fragmentary section of the pressing device taken along the line IIIIII in FIG. 1, and

FIG. 4 is a sectional view taken along the line IVIV in FIG. 3.

Referring now to FIG. 1 of the drawings, a preferred embodiment of the pressing device of this invention, generally designated by a, is diagrammatically shown installed on a wide belt sander machine 10. The marking 10 comprises a frame 12, a work table 14 adapted to be vertically moved up and down by means of a reciprocator 16 such as threaded rod-gear means fixed on said frame 12. There is also provided a control handle 18, two guide. rolls 22 and 24, a driving roll 26, a tension roll 28 respectively mounted rotatably on a roll support member 20 vertically standing on said frame 12. Finally, the machine 10 includes an endless sander belt 30 of a width substantially corresponding to that of said table 14 and adapted to be driven around the rolls 22, 24, and 28 by means of said driving roll 26 which is rotated by a motor (not shown). The device a of the present invention is shown to be fixedly mounted on the roll support member 20 for the sake of clear and simple illustration. However, it is of course possible and rather preferable to mount said device a removably to said roll support member 20. The lower ends of the device project slightly with respect to the lower surface of the guide rolls 22 and 24 to press the lower horizontal run of the sander belt 30 downwardly. After setting the table 14, which can be raised and lowered by means of the threaded rod means 16 and the handle 18, at a level to be determined by the thickness of a workpiece b, said workpiece b is fed into the belt sander machine in the direction as shown by an arrow 0 along the table 14by any feeding operation means (not shown). During the feeding the workpiece b is subjected to sand-finishing action of the sander belt 30 driven in the direction d and pressed downwardly by the device a of the present invention. The particles removed by the belt 30 are discharged through a duct 32 provided with an appropriate sucking or blowing means (not shown).

Referring next to FIG. 2, the device a of the present invention is mounted on a simple belt sander machine which comprises a frame 34, a bed 38 adapted to be vertically moved up and down by means of a reciprocator means 36, a horizontally movable table 40 with rollers 401 rotatable on rails 42 mounted on said bed 38, a driving roll 44 and an idler roll 46 around which an endless sander belt 48 is extended to be driven by any suitable motor means (not shown). On the upper end of said frame 34 is mounted or formed a guide member 50 which slidably carries a holder member 52 for the means a of the present invention to enable the means a to be moved across the entire width of the table 40. The workpiece fixedly supported on said table 40 may move horizontally and normal to the direction of movements of the belt 48, the inner surface portion of which is pressed down by the device a positioned between the rolls 44 and 46 The means a is fixedto the holder. block 52, which holder block is slidably movable along said guide means 50 in the direction normal to the direction of movement of the workpiece.

In FIGS. 3 and 4 there is illustrated in more detail the device of the present invention generally designated by a which may be mounted integrally or removably by any desired conventional means to the lower portion of the roll support member as designated by the numeral in FIG. 1 or the holder block as represented by 52 in FIG. 2. The device a comprises a housing 54 having a substantially channel-like cross section (see FIG. 4) which is provided on the upper portion thereof with outwardly projecting flanges 541 and 542 to fit slidably in the roll support member or the holder block. Leg portions 543 and 544 of said channel-like housing are respectively bent inwardly at the respective free ends thereof so as to form a channel cavity in which there is disposed a deformable bag 56 made of a flexible material and expandable into a substantially rectangular shape when supplied with fluid such as air under pressure through an inlet 60 from any suitable source (not shown). Under said deformable bag 56 is positioned an intermediate means which consists of a plurality of metallic rods 58 arranged in parallel so that the axle of each said rods 58 is parallel to the direction of the sander belt movement. The cross-section of each of said rods 58 may be of any desired shape such as a square or circle. The ends of said rods 58 preferably rest respectively on the inwardly bent ends 543 and 544 of the housing legs which serves to prevent the air bag 56 from being forced out of the housing even if an excess of air is supplied thereinto through the inlet 60. Under said rods 58 there is provided a deformable member 64 made of any desired flexible material, which material defines an overall pressure element. The member 64 is mounted so that the lower portion thereof projects out of the channel cavity of the housing when the air under pressure is supplied itno said air bag 56. In order to cover the open end of said cavity, a closure member 62 is provided which is preferably made of wear resistant material such as leather, glass fiber cloth, which closure member 62 contacts the inner surface of the sander belt to press it downwardly. The closure member 62 is fixed to the housing at the ends thereof in the tensile condition by any appropriate means such as bolts 70 and washers 72 as shown in FIG. 4.

Between the rods 58 and the air bag 56 and between the air bag 56 and the overall pressure element 64 there may be provided respectively flexible sheet members 66a and 6611 made of sheet metal, rubber sheet, cloth or the like. The device a will, however, function adequately without said flexible sheet members, however.

When the pressure of the fluid such as air in the deformable bag 56 is adjusted so that the oposite ends of the parallelly arranged rod respectively are urged against the inwardly bent leg free ends 543 and 544, the pressure element presses the sander belt 68 against the workpiece. Thus, if the wood workpiece b on the table of the belt sander machine is warped the cover member 62 and the flexible body 64 will be deformed to displace the rods 58 such that they will conform to the shape of the workpiece and thus effect complete sanding.

From the foregoing disclosure of a preferred embodiment, the present invention will be easily understood by those skilled in the art but it should be noted that said disclosure has been given merely by way of explanation of the invention and various changes or modifications in the shape, construction and arrangement of parts as well as material thereof may be made Without departing from the spirit and the scope of the claims as clearly set forth in claims hereinafter.

What is claimed is:

1. A device for pressing the sander belt of a sanding machine against a workpiece, said device comprising a housing having an open end and an abutment surface adjacent to said open end, a plurality of rods resting on said abutment surface and arranged parallel to each other and to the direction of movement of the sander belt, a deformable container in said housing and fillable with fluid under pressure to urge said rods against said abutment surface, and a flexible pressure element carried by said housing and partly projecting through the opening therein for operative engagement with the sander belt, thereby to press the sander belt against the workpiece to effect sanding thereof despite the presence of irregularities in the workpiece extending parallel to the direction of movement of the sander belt.

2. The device set forth in claim 1, wherein said housing is of channel-like construction and has a pair of legs, the outer ends of said legs being bent inwardly to define said abutment surface upon which said rods rest.

3. The device set forth in claim 1, and further comprising a flexible cover member covering said pressure element and secured to said housing, thereby to hold together said deformable container and said rods and said pressure element.

References Cited UNITED STATES PATENTS 3,283,447 11/1966 Cretsinger 51-141 3,408,775 11/1968 Rutt 51141 X 3,429,079 2/1969 Winebarger 51148 X OTHER REFERENCES German printed application No. B37580, Nov. 8,1956, Bottcher.

OTHELL M. SIMPSON, Primary Examiner 

